发布时间: 2017-12-11 14:24:00
参考: https://stackoverflow.com/a/43892850
year = 2017 month = 5 require 'date' Date.new(year, month, 1) #=> #<Date: 2017-05-01 ...> Date.new(year, month, -1) #=> #<Date: 2017-05-31 ...>